1. Field of the Invention
The present invention relates to a jitter measurement circuit which measures jitter included in a cyclic signal.
2. Description of the Background Art
In recent years, there are seen the acceleration of the main clock bus of a personal computer, the emergence of high-rate interfaces such as IEEE-1394 interface, the rapid rising of digital radio transmission such as cellular phones or radio LAN including the Bluetooth and the like. Following them, the potential needs of the measurement of jitter are generally rising.
There is known a jitter measurement method including quantizing a signal outputted from a measurement target object in the same cycle, and measuring the jitter of the signal in real time on the basis of the change of the quantized output data, as disclosed in Japanese Patent Laying-Open No. 2000-292469.
Meanwhile, as equipment for measuring such jitter, a time interval analyzer which has an analysis function of, for example, continuously, completely measuring the time intervals of measurement target signals to capture a large quantity of data and displaying a time interval histogram, and a spectrum analyzer, which analyzes the spectrum of a signal, as well as an analog tester which equally functions to these measuring equipment are employed. Recently, a mix signal tester which tests a digital/analog mixed IC in which digital signals and analog signals called mixed signals are used, i.e., a mixed device, and which functions equally to those described above, has appeared.
However, if a jitter measurement system is constructed with such measurement equipment or tester, it disadvantageously is expensive and takes a long time to construct. In addition, the tester having a jitter measurement function is disadvantageously expensive.